Blackhall Rocks – again!

DWT Botany Group DWT Botany Group, News


Keith Robson describes the latest, and final, botanical survey for this year of this wonderful stretch of the Durham coastline.

Five intrepid members of the DWT Botany group met in the car park at Blackhall Rocks to survey the final six wet flushes on the slopes of this wonderful site. The weather forecast was showers, some heavy, but we bravely carried on, and as it happens on this coast it decided to have its own weather system, a bit breezy but dry throughout. There were two members of the group on their first outing with us so we all introduced ourselves, ran through the Health & Safety checks and off we set. The cliff slopes where we were surveying at the southern end are quite steep and care had to be taken. Often the easiest way was to slide down on your bottom!

The first of the six areas to be checked was just south of the car park. Initially it did not look very good with considerable encroachment from Equisetum telmateia (Great Horsetail), Rubus fruticosus agg. (Bramble) and Cirsium arvense (Creeping Thistle) throughout and a large, spreading patch of Aegopodium podagraria (Ground-elder) at the top. However, when we got to work we discovered it held a good population of Serratula tinctoria (Saw-wort). This plant initially looks like a spineless thistle but has saw-toothed leaves from where it gets its name. Though nearly all had finished flowering there were many Neottia ovata (Common Twayblade) on these slopes too and Tom found on a little outcrop, the only Scabiosa columbaria (Small Scabious) of the day.

 

Gymnadenia conopsea

Agrimonia eupatoria

The second area was wet on the lower slopes as shown by the patch of Phragmites australis (Common Reed) and Epilobium hirsutum (Great Willow-herb) but rather dry nearer the top allowing the grasses to be quite rank. Much of this was Arrhenatherum elatius (False Oat-grass) but a number of other species were present both here and at the other spots, allowing us to test our grass and sedge identification skills throughout the day. Our first Gymnadenia conopsea (Fragrant Orchid), again many having finished flowering, were found, some still giving off a strong sweet orangey perfume. Notable here was the amount of Agrimonia eupatoria (Agrimony), which was scattered throughout the survey area. The yellow spikes smell of apricots and it is a member of the rose family, unlike Eupatorium cannabinum (Hemp Agrimony), also present here but not being a thug like in the northern part of the reserve.

The third area was very dry and dominated with Brachypodium sylvaticum (False Brome) (we all had our eye in now for this species with its hairy yellow-green leaves and drooping inflorences) and Equisetum arvense (Field Horsetail). The latter was scattered throughout but not creating thickets like its relative Equisetum telmateia (Great Horsetail) to the north. More, and the last, the Saw-wort plants were seen and the only Anthyllis vulneraria (Kidney Vetch) of the day.

 

Trifolium medium

We had completed half by 12:30 so it was time for our lunch which we ate on the slopes out of the wind, before we carried on with number four or Flush Compartment #38 on our map. Here more Common Reed but half way up the slope this time. At the top the water seeps out and trickles to the depression where the stand of reed is but the nature of the geology here means bits of the slope are always slipping down leaving bare wet areas. This creates ideal habitat for Pinguicula vulgaris (Common Butterwort) with 20 plants here, together with Carex pulicaris (Flea Sedge) and some Thymus polytrichus (Wild Thyme) on the dry area just above. There were also some tiny Centaurium erythraea (Common Centuary) plants here that were scrutinised in case they were something rarer but unfortunately were not.

 

Leontodon hispidus

We were here to examine slippages and the next was near the steps to the beach known locally as Green Stairs. When we arrived there was a slippage and it had carried away some of the stairs and the steps were closed off for safety. This is a new slippage and should go on the map. We however using the 10-figure grid reference were to survey the one slightly to the south and the lack of steps wasn’t going to stop us, none of the others had steps anyway. There were 50 more Butterwort here and the largest patch of Helianthemum nummularium (Common Rock-rose) of the day. With there being steps to the beach, the adjacent path had been well used and it was interesting to note the number of ruderals (plant species that are first to colonize disturbed ground) that were here compared to the other areas.

With our final survey area in sight we moved on to number 6 of the day (or 40 on the map). This was a rather small area in the middle of the slope but there was evidence of recent slippage. A large population of 80+ Common Butterwort were seen together with the only population of Polygala vulgaris (Common Milkwort) in these southern sections and a large area dominated by Trifolium medium (Zigzag Clover). This latter species was looking particularly showy with its reddish-purple flowers and easily identified from its Trifolium pratense (Red Clover) cousin by its ‘zig-zag’ stems, and thin, narrow leaves.

We were all rather pleased when we had finished as the climbing up and down the slopes is very tiring on the old legs. 110 species were recorded with the populations of Common Butterwort probably being the highlight. No Primula farinose (Bird’s-eye Primrose) could be found again despite some very suitable spots and lots of diligent searching but there were many other interesting sightings instead. Hard work but enjoyed by all.

For a full species list click here 

Thank you to Keith Robson for his very detailed report and species list. This was a great effort from the team; Carole, Keith A, Keith R Steve and Tom from Natural England. Thank you all and to those members who joined surveys earlier in the year. We await a full report, from mark Dinning, on the current botanical status of this stretch of the coast. This will inform  ongoing conservation management by Durham Wildlife Trust.

If you are interested in wild plants and vegetation of all kinds, the DWT botany group is for you! For more details email botany@durhamwt.co.uk